1. Field of the Invention
The present invention is generally related to a marine transmission actuator and, more particularly, to a hydraulic valve that is configured to move a hydraulic actuator into forward, neutral, and reverse gear positions and cause the actuator to remain in those positions until a subsequent change occurs with regard to the hydraulic valve.
2. Description of the Related Art
Those skilled in the art of marine propulsion devices are familiar with many different types of gear position actuators that can be used by an operator of a marine vessel to change the gear position of the marine transmission between forward, neutral, and reverse gear positions. Many of these types of transmissions are mechanical. Others use hydraulic pressure to assist in the gear shifting operation. Some systems use electromechanical components.
U.S. Pat. No. 3,623,583, which issued to Shimanckas on Nov. 30, 1971, describes an electrically operated control mechanism for a hydraulic shifting mechanism. It includes a hydraulic mechanism that is operative to effect shifting of a clutch from a fail-safe forward drive condition to either of a neutral or reverse condition. It also includes an electrically operated control mechanism for the hydraulic mechanism, which is also designed to fail-safe in forward drive. The control mechanism includes aligned, neutral and rearward drive solenoids which are selectively energizeable to afford neutral and reverse drive and which are operably associated with a single plunger carrying a spool valve embodied in the hydraulic system.
U.S. Pat. No. 3,858,101, which issued to Schmiedel et al. on Dec. 31, 1974, discloses a shift motor actuator circuit. A DC motor includes the conventional separate reverse winding and forward winding, each of which is connected individually in series with the motor armature of a battery through motor driven limit switches to stop at neutral, forward or reverse drive positions. The armature is connected to drive a valve for actuating a hydraulic shift unit. A resistor and a diode are connected in parallel between the power side of each winding and ground. The resistor acts as an electrical load and eliminates hunting of the drive system and the repeated operation of the limit switches. The resistors employed are relatively low wattage type so as to burn open in a relatively short period and without a flame or mass heat characteristic capable of igniting fuel fumes associated with recreational type marine propulsion devices. The diodes are back biased by the battery polarity but conduct transient voltages of the opposite polarity which may arise in the motor circuit.
U.S. Pat. No. 5,301,922, which issued to Hayasaka on Apr. 12, 1994, describes a changeover valve means for a hydraulic clutch of the marine propulsion unit. A drive system that includes a bevel gear forward, reverse transmission has hydraulically operated clutches. A hydraulic pump for actuating the clutches and lubricating the transmission is driven off the rear end of the input shaft and control valve means selectively communicates the fluid from the hydraulic pump with the hydraulic clutches. The valve means is a rotary plug type valve but is constructed so as to minimize axial and radial forces acting that would tend to bind its movement.
U.S. Pat. No. 5,328,396, which issued to Hayasaka on Jul. 12, 1994, describes a power transmission system for an inboard/outboard motor. A hydraulic pump for actuating clutches and for lubricating the transmission is driven off the rear end of the input shaft and control valve means selectively communicates the fluid from the hydraulic pump with the hydraulic clutches. The valve means is a rotary plug type valve but is constructed so as to minimize axial and radial forces acting that would tend to bind its movement. The construction of the outboard drive unit is such that the bevel gear transmission and hydraulically operated clutches can conveniently be inserted through like diameter oppositely facing openings formed in the upper end of the housing assembly of the outboard drive unit.
U.S. patent application Ser. No. 11/242,028, which was filed on Oct. 4, 2005 by Harada et al., describes a marine reversing gear assembly. A manual directional control valve and an electromagnetic directional control valve for a forward/reverse directional control valve for hydraulic oil supply circuit have a common structure of an oil line joint surface for the hydraulic oil supply circuit for friction discs of a forward clutch and a reverse clutch.
U.S. patent application Ser. No. 11/330,096, which was filed on Jan. 12, 2006 by Okanishi et al., describes a marine reversing gear assembly provided with a locking device. The system provides a self-contained marine reversing gear assembly provided with a locking device for internal combustion engine in which introduction of the working oil from the lubricating oil circuit is unnecessary. The marine reversing gear assembly provided with a locking device comprises an input shaft driven by an internal combustion engine, an output shaft connected to a propeller shaft, a hydraulic pump driven by the input shaft, a hydraulic forward and reverse clutch, a directional control valve for switching the forward and reverse clutch by the supply of working oil from the hydraulic pump, and a locking device provided with a locking mechanism member for locking the output shaft. The locking device comprises a hydraulic actuator for unlocking the output shaft by operating on the locking mechanism member due to the supply of working oil from the hydraulic pump.
U.S. patent application Ser. No. 11/786,821; which was filed on Apr. 13, 2007 (M10112) by Phillips et al., discloses an actuator device for a marine propulsion transmission. The actuator is attached to a movable clutch member through the use of a coupler which comprises a generally spherical member formed as a portion of the actuator and a chuck device formed as part of the clutch member. The generally spherical member, or alternatively shaped component, is received by the chuck device and retained therein. The components are configured to allow relative rotation between the actuator and the clutch member while causing them to move axially in synchrony with each other.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
In marine transmissions, it is significantly beneficial if the structure of the transmission can be simplified as much as possible while providing a generally rugged and durable structure. Hydraulically assisted gear shifting mechanisms are known to those skilled in the art. It would be significantly beneficial if a hydraulically assisted shifting mechanism could reliably move a clutch mechanism into forward, neutral, or reverse gear positions without the need for position sensing devices that detect whether or not the clutch has been moved to the proper position. In addition, it would be beneficial if such a hydraulically actuator gear shifting mechanism could be provided with a rugged and reliable hydraulic valve that moves the clutch into the proper position and maintains the clutch in that selected position until subsequent movement of the hydraulic valve which is actuated by a manually operable gear shift lever.